This invention relates generally to electrostatographic apparatus and, more particularly, to radiant energy apparatus for fixing toner images to a support member.
In the process of electrostatography, latent electrostatic images are formed on a support member, for example, plain paper with the subsequent rendering of the latent images visible by the application of electroscopic marking particles, commonly referred to as toner. The toner or powder images so formed vary in density in accordance with the magnitude of electrostatic charges forming the individual images.
The toner images can be fixed directly upon the support member on which they are formed or they can be transferred to another support member with subsequent fixing of the images thereto.
Fixing of toner images can be accomplished by various methods one of which is by the employment of thermal energy. In order to permanently fix or fuse toner images onto a support member by means of thermal energy it is necessary to elevate the temperature of the toner material to a point at which the constituents of the toner coalesce and become tacky or melt. This action causes the toner to be absorbed to some extent into the fibers of the paper. Thereafter, as the toner cools, solidification of the toner material occurs causing it to be firmly bonded to the support member. In the process of electrostatography, the use of thermal energy for fixing toner images is old and well known.
One aproach to thermal fixing or fusing of toner images onto a support member is to pass the support member with the toner images thereon past a source of radiant energy such that the image-bearing side of the support is opposite the source of radiation while the reverse side thereof is moved in contact with a support platen which may be heated.
It will be appreciated by those skilled in the art that during simplex (i.e. single-sided copying) operation, it is desirable to prevent contacting of the radiant heat source by the copy paper and the toner images otherwise the paper may become scorched and the toner would contaminate the energy source. Additionally, during duplex operation (i.e. copying on both sides of a support) of the type herein contemplated it is desirable to prevent the toner images from the first side of the copy paper offsetting to the platen and or belts which come in contact with the toner images which images are again softened by the energy sources employed.
Accordingly, it is the primary object of this invention to provide a new and improved radiant fuser for use in an electrostatographic apparatus.
It is a more particular object of this invention to provide, in a xerographic reproducing apparatus, a radiant fuser and method of fusing toner images to support sheets wherein transport means operatively associate with the fuser serve to transport the copy sheet and toner images carried thereby through the fuser without the components of the fuser being contacted by either the paper or the toner images.
Another object of the invention is to provide a new and improved radiant fuser and method of fusing toner images to support sheets wherein a first transport is provided for initially moving the copy sheets partially through the fuser without contacting the components thereof and a second transport cooperating with the first transport to move the copy sheet the rest of the way through the fuser without contacting the components of the fuser, particularly, by the trailing edge of the support sheet.
Still another object of the invention is to provide a new and improved fuser for fixing toner images to support sheets and the method of fusing toner images to support sheets wherein a first transport is provided for corrugating the copy paper to thereby increase the beam strength thereof along the axis of travel and to thereby control the leading edge of the support sheet during its movement through the fuser and means for maintaining the corrugations in the paper as the trailing edge of the support sheet moves through the fuser.